<template>
  <div>
    <h2>我是Child组件</h2>
    <button @click="handler">累加app中的count</button>
  </div>
</template>

<script>
export default {
  name: "Child",
  methods: {
    handler() {
      this.$emit("changeCount", 3);
    },
  },
};
</script>

<style>
</style>